Lots of testing of various stores under various situations. As you know SIS has been eliminated from Exchange 2010 and a form of store compression introduced. This, along with the other capabilities of the NetApp platform have played right into our hands. NetApp is the only vendor to offer deduplication on primary data. The deduplication is not an in-line process but rather is scheduled. Hourly, twice daily, daily, weekly, whatever. You set it to suit your requirements.